This occurred to me watching all the car maintenance programs on TV.
And merging that with increasingly good standards of vehicle exhaust pollution.

A lot of effort goes into making manifolds with smooth flow and with arms of equal length, in order to improve engine performance.

Given the reductions in vehicle exhaust emissions, it is no longer necessary to duct the exhaust all the way to the back of the car before releasing it. It could perhaps be released at the side of the engine bay like the some of the old hot rods (see image below), or under the centre of the car, or perhaps even in the engine bay if the air intakes are outside.

Catalytic converters can be small, it’s possible to buy cars now that have catalytic converters within the manifold.

The problem then is the muffler. Mufflers are big, and the better the engine performance, the bigger the muffler has to be. Thirty inches long is something of a minimum.

And that leads me to active noise cancellation, like that in headphones. eg. https://cecas.clemson.edu/cvel/auto/systems/active_exhaust_noise_cancellation.html Active noise cancellation is already used in some cars, but not for cancelling noise. It’s currently used for changing the pitch of the exhaust, and for making it louder, for rev-heads.

If I’m right, a noise cancelling muffler can be made directly from a catalyic converter without any signifiant change in length. A microphone downstream of the converter feeds to a speaker upstream that cancels out the noise. For sound absorbance behind the speaker some sound deadening material can be used or, better, a vaccum because a vacuum doesn’t transmit sound.

Put one on the outlet of each cylinder and voila, silence without an exhaust manifold and negligible power loss in the exhaust beyond that needed for the catalytic converter.

Side exhausts.

Inline active noise cancelling.

Do they still use platinum in catalytic converters?

mollwollfumble said:

This occurred to me watching all the car maintenance programs on TV.
And merging that with increasingly good standards of vehicle exhaust pollution.

A lot of effort goes into making manifolds with smooth flow and with arms of equal length, in order to improve engine performance.

Given the reductions in vehicle exhaust emissions, it is no longer necessary to duct the exhaust all the way to the back of the car before releasing it. It could perhaps be released at the side of the engine bay like the some of the old hot rods (see image below), or under the centre of the car, or perhaps even in the engine bay if the air intakes are outside.

Catalytic converters can be small, it’s possible to buy cars now that have catalytic converters within the manifold.

The problem then is the muffler. Mufflers are big, and the better the engine performance, the bigger the muffler has to be. Thirty inches long is something of a minimum.

And that leads me to active noise cancellation, like that in headphones. eg. https://cecas.clemson.edu/cvel/auto/systems/active_exhaust_noise_cancellation.html Active noise cancellation is already used in some cars, but not for cancelling noise. It’s currently used for changing the pitch of the exhaust, and for making it louder, for rev-heads.

If I’m right, a noise cancelling muffler can be made directly from a catalyic converter without any signifiant change in length. A microphone downstream of the converter feeds to a speaker upstream that cancels out the noise. For sound absorbance behind the speaker some sound deadening material can be used or, better, a vaccum because a vacuum doesn’t transmit sound.

Put one on the outlet of each cylinder and voila, silence without an exhaust manifold and negligible power loss in the exhaust beyond that needed for the catalytic converter.

Side exhausts.

Inline active noise cancelling.

Looks heavy, complex & expensive compared to cheap mufflers.

Tamb said:

Looks heavy, complex & expensive compared to cheap mufflers.

Indeed were it not for the fossil fuel industrial interests holding back the market, lighter, simpler, cheaper, cleaner and quieter vehicles would already be widespread, even numerically dominant, on our roads.

there’s always that period you first start the vehicle, takes time for engine to warm up, exhaust, hot box and all, and in cold conditions it’s longer again

you can add also that the pollution control that burns to the recycled gasses/vapors from the sump, from piston ring bypass etc, as the vehicle ages piston/piston ring bypass increase, again a problem with an engine and exhaust that isn’t up to optimum temperature

there probably are limits to how fast the engine temperature can be ramped up with a closed thermostat, influences engine longevity, related maximum piston cap expansion-rate relative to bore diameter, but there are other practical limitations regard that, like difference in temperature between different volumes of water in the heat exchange arrangement, and equalizing them

speaking of,
https://www.abc.net.au/news/2021-04-11/carbon-dioxide-levels-reach-historic-high-of-421ppm/100058596

Tamb said:

mollwollfumble said:

This occurred to me watching all the car maintenance programs on TV.
And merging that with increasingly good standards of vehicle exhaust pollution.

A lot of effort goes into making manifolds with smooth flow and with arms of equal length, in order to improve engine performance.

Given the reductions in vehicle exhaust emissions, it is no longer necessary to duct the exhaust all the way to the back of the car before releasing it. It could perhaps be released at the side of the engine bay like the some of the old hot rods (see image below), or under the centre of the car, or perhaps even in the engine bay if the air intakes are outside.

Catalytic converters can be small, it’s possible to buy cars now that have catalytic converters within the manifold.

The problem then is the muffler. Mufflers are big, and the better the engine performance, the bigger the muffler has to be. Thirty inches long is something of a minimum.

And that leads me to active noise cancellation, like that in headphones. eg. https://cecas.clemson.edu/cvel/auto/systems/active_exhaust_noise_cancellation.html Active noise cancellation is already used in some cars, but not for cancelling noise. It’s currently used for changing the pitch of the exhaust, and for making it louder, for rev-heads.

If I’m right, a noise cancelling muffler can be made directly from a catalyic converter without any signifiant change in length. A microphone downstream of the converter feeds to a speaker upstream that cancels out the noise. For sound absorbance behind the speaker some sound deadening material can be used or, better, a vaccum because a vacuum doesn’t transmit sound.

Put one on the outlet of each cylinder and voila, silence without an exhaust manifold and negligible power loss in the exhaust beyond that needed for the catalytic converter.

Side exhausts.

Inline active noise cancelling.

Looks heavy, complex & expensive compared to cheap mufflers.

It does, but it’s probably none of the three.
I can guarantee a weight reduction of 90%, actually more like 100%, for the total exhaust system.
The technology is the same as noise cancelling headphones, which are not expensive.
And much less complicated than resonant chamber mufflers.

It’s the equivalent of replacing an analogue computer (resonant muffler) by a digital computer.

Another car with side exhausts.

SCIENCE said:

speaking of,
https://www.abc.net.au/news/2021-04-11/carbon-dioxide-levels-reach-historic-high-of-421ppm/100058596

So not much has changed then.

you don’t want exhaust vapors (or noise) to the side of a vehicle, the best place is out the back

Side exhasts.. extractors.

Any impedance will reduce their effectiveness.

SCIENCE said:

speaking of,
https://www.abc.net.au/news/2021-04-11/carbon-dioxide-levels-reach-historic-high-of-421ppm/100058596

Speaking of. Carbon dioxide levels per vehicle km reach all-time low.
See thread on air pollution for details. https://tokyo3.org/forums/holiday/topics/14874/
Apart from that, CO2 doesn’t stink.

mollwollfumble said:

SCIENCE said:

speaking of,
https://www.abc.net.au/news/2021-04-11/carbon-dioxide-levels-reach-historic-high-of-421ppm/100058596

Speaking of. Carbon dioxide levels per vehicle km reach all-time low.
See thread on air pollution for details. https://tokyo3.org/forums/holiday/topics/14874/
Apart from that, CO2 doesn’t stink.

Cars put out CO
Is the CO2 from their manufacture?

UNDESIRABLE EMISSIONS IN INTERNAL COMBUStion engines are of major concern beause of their negative impact on air quality, human health, and global warming. Therefore, there is a concerted effort by most governments to control them. Undesirable emissions include unburned hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NOx), and particulate matter (PM). In this chapter, we present the U.S. and European emissions standards, both for gasoline and diesel operated engines, and strategies to control the undesirable emissions. The role of engine design, vehicle operating variables, fuel quality, and emission control devices in minimizing the above-listed pollutants are also detailed in this chapter. “Emissions” is a collective term that is used to describe the undesired gases and particles which are released into the air or emitted by various sources, Its amount and the type change with a change in the industrial activity, technology, and a number of other factors, such as air pollution regulations and emissions controls . The U.S. Environmental Protection Agency (EPA) is primarily concerned with emissions that are or can be harmful to the public at large. EPA considers carbon monoxide (CO), lead (Pb), nitrogen dioxide (NO2), ozone (O3), paniculate matter (PM), and sulfur dioxide (SO2) as the pollutants of primary concern, called the Criteria Pollutants. These pollutants originate from the following four types of sources. 1. Point sources, which include facilities such as factories and electric power plants. 2. Mobile sources, which include cars and trucks but also lawn mowers, airplanes, and anything else that moves and releases pollutants into the air. 3. Biogenic sources, which include trees and vegetation, gas seeps, and microbial activity. 4. Area sources, which consist of smaller stationary sources such as dry cleaners and degreaslng operations. https://www.astm.org/DIGITAL_LIBRARY/MNL/PAGES/MNL11466M.htm

mollwollfumble said:

Tamb said:

mollwollfumble said:

This occurred to me watching all the car maintenance programs on TV.
And merging that with increasingly good standards of vehicle exhaust pollution.

A lot of effort goes into making manifolds with smooth flow and with arms of equal length, in order to improve engine performance.

Given the reductions in vehicle exhaust emissions, it is no longer necessary to duct the exhaust all the way to the back of the car before releasing it. It could perhaps be released at the side of the engine bay like the some of the old hot rods (see image below), or under the centre of the car, or perhaps even in the engine bay if the air intakes are outside.

Catalytic converters can be small, it’s possible to buy cars now that have catalytic converters within the manifold.

The problem then is the muffler. Mufflers are big, and the better the engine performance, the bigger the muffler has to be. Thirty inches long is something of a minimum.

And that leads me to active noise cancellation, like that in headphones. eg. https://cecas.clemson.edu/cvel/auto/systems/active_exhaust_noise_cancellation.html Active noise cancellation is already used in some cars, but not for cancelling noise. It’s currently used for changing the pitch of the exhaust, and for making it louder, for rev-heads.

If I’m right, a noise cancelling muffler can be made directly from a catalyic converter without any signifiant change in length. A microphone downstream of the converter feeds to a speaker upstream that cancels out the noise. For sound absorbance behind the speaker some sound deadening material can be used or, better, a vaccum because a vacuum doesn’t transmit sound.

Put one on the outlet of each cylinder and voila, silence without an exhaust manifold and negligible power loss in the exhaust beyond that needed for the catalytic converter.

Side exhausts.

Inline active noise cancelling.

Looks heavy, complex & expensive compared to cheap mufflers.

It does, but it’s probably none of the three.
I can guarantee a weight reduction of 90%, actually more like 100%, for the total exhaust system.
The technology is the same as noise cancelling headphones, which are not expensive.
And much less complicated than resonant chamber mufflers.

It’s the equivalent of replacing an analogue computer (resonant muffler) by a digital computer.

Another car with side exhausts.

That last photo shows one of the simplest and best ways to get rid of most of the noise from an exhaust: Put it through a turbocharger.

roughbarked said:

mollwollfumble said:

SCIENCE said:

speaking of,
https://www.abc.net.au/news/2021-04-11/carbon-dioxide-levels-reach-historic-high-of-421ppm/100058596

Speaking of. Carbon dioxide levels per vehicle km reach all-time low.
See thread on air pollution for details. https://tokyo3.org/forums/holiday/topics/14874/
Apart from that, CO2 doesn’t stink.

Cars put out CO
Is the CO2 from their manufacture?

UNDESIRABLE EMISSIONS IN INTERNAL COMBUStion engines are of major concern beause of their negative impact on air quality, human health, and global warming. Therefore, there is a concerted effort by most governments to control them. Undesirable emissions include unburned hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NOx), and particulate matter (PM). In this chapter, we present the U.S. and European emissions standards, both for gasoline and diesel operated engines, and strategies to control the undesirable emissions. The role of engine design, vehicle operating variables, fuel quality, and emission control devices in minimizing the above-listed pollutants are also detailed in this chapter. “Emissions” is a collective term that is used to describe the undesired gases and particles which are released into the air or emitted by various sources, Its amount and the type change with a change in the industrial activity, technology, and a number of other factors, such as air pollution regulations and emissions controls . The U.S. Environmental Protection Agency (EPA) is primarily concerned with emissions that are or can be harmful to the public at large. EPA considers carbon monoxide (CO), lead (Pb), nitrogen dioxide (NO2), ozone (O3), paniculate matter (PM), and sulfur dioxide (SO2) as the pollutants of primary concern, called the Criteria Pollutants. These pollutants originate from the following four types of sources. 1. Point sources, which include facilities such as factories and electric power plants. 2. Mobile sources, which include cars and trucks but also lawn mowers, airplanes, and anything else that moves and releases pollutants into the air. 3. Biogenic sources, which include trees and vegetation, gas seeps, and microbial activity. 4. Area sources, which consist of smaller stationary sources such as dry cleaners and degreaslng operations. https://www.astm.org/DIGITAL_LIBRARY/MNL/PAGES/MNL11466M.htm

They also put out loads of CO2 (much more than the other undesirables listed above).

roughbarked said:

Side exhasts.. extractors.

Any impedance will reduce their effectiveness.

Exactly!

A straight length of pipe 200 mm long provides less impedence than 2000 mm long with multiple obstructions.

> you don’t want exhaust vapors (or noise) to the side of a vehicle, the best place is out the back

Why not, given that the exhaust contains nothing but pure CO2 and the noise levels are lower?
(I can actually see why not, it’s not either the exhaust vapours or noise. It’s the heat. Care is needed to avoid burning people on the hot exhaust.

> cost

As for cost, some high end sports cars already have them, but use them to change the pitch and tone of the exhaust, and make it louder, rather than to quieten it.

I think I can come up with a better design than that by https://cecas.clemson.edu/cvel/auto/systems/active_exhaust_noise_cancellation.html
Start with a slight expansion (perhaps 20%) directly off the engine exhaust port, this already eases back pressure enormously. On the sides of this expansion insert piezoelectric speakers backed by a narrow torus of vacuum. Then the catalytic converter directly downstram of the expansion, then a 45 degree bend and finally a few piezoelectric microphones near the end.

If the exhaust is under the centre of the car then add a length of pipe to get there.
If the exhaust is in the engine bay then add an external air intake.
If the exhaust is at the side of the car then add a cooler.

Michael V said:

mollwollfumble said:

Tamb said:

Looks heavy, complex & expensive compared to cheap mufflers.

It does, but it’s probably none of the three.
I can guarantee a weight reduction of 90%, actually more like 100%, for the total exhaust system.
The technology is the same as noise cancelling headphones, which are not expensive.
And much less complicated than resonant chamber mufflers.

It’s the equivalent of replacing an analogue computer (resonant muffler) by a digital computer.

Another car with side exhausts.

That last photo shows one of the simplest and best ways to get rid of most of the noise from an exhaust: Put it through a turbocharger.

That is a really good solution.

>Why not, given that the exhaust contains nothing but pure CO2 and the noise levels are lower?
(I can actually see why not, it’s not either the exhaust vapours or noise. It’s the heat. Care is needed to avoid burning people on the hot exhaust.

did you miss what I said about a cold engine and exhaust, how long they take to come up to temperature

> Cars put out CO

If CO was a problem, then cars wouldn’t be allowed to have rear exhausts either. Rear exhausts were approved when CO output was much higher.

CO has surprisingly low toxicity (or we’d die each time we sat in front of a camp fire).
CO levels are already way down, due to catalytic converters.

> Is the CO2 from their manufacture?

It’s from the fuel. Fuel plus air in gives CO2 + H2O + N2 out, plus pollution.

transition said:

>Why not, given that the exhaust contains nothing but pure CO2 and the noise levels are lower?
(I can actually see why not, it’s not either the exhaust vapours or noise. It’s the heat. Care is needed to avoid burning people on the hot exhaust.)

did you miss what I said about a cold engine and exhaust, how long they take to come up to temperature

Huh? I don’t see the relevence.

Are you claiming it takes too long a time or too short a time? And are you talking about engine temperature or exhaust temperature?

mollwollfumble said:

> Cars put out CO

If CO was a problem, then cars wouldn’t be allowed to have rear exhausts either. Rear exhausts were approved when CO output was much higher.

CO has surprisingly low toxicity (or we’d die each time we sat in front of a camp fire).
CO levels are already way down, due to catalytic converters.

> Is the CO2 from their manufacture?

It’s from the fuel. Fuel plus air in gives CO2 + H2O + N2 out, plus pollution.

Well while you burn fuel, it is never goiing away.

mollwollfumble said:

transition said:

>Why not, given that the exhaust contains nothing but pure CO2 and the noise levels are lower?
(I can actually see why not, it’s not either the exhaust vapours or noise. It’s the heat. Care is needed to avoid burning people on the hot exhaust.)

did you miss what I said about a cold engine and exhaust, how long they take to come up to temperature

Huh? I don’t see the relevence.

Are you claiming it takes too long a time or too short a time? And are you talking about engine temperature or exhaust temperature?

You don’t get exhaust temperature without engine temperature.

The Rev Dodgson said:

roughbarked said:

mollwollfumble said:

Speaking of. Carbon dioxide levels per vehicle km reach all-time low. See thread on air pollution for details. https://tokyo3.org/forums/holiday/topics/14874/
Apart from that, CO2 doesn’t stink.

Cars put out CO
Is the CO2 from their manufacture?

UNDESIRABLE EMISSIONS IN INTERNAL COMBUStion engines are of major concern beause of their negative impact on air quality, human health, and global warming. Therefore, there is a concerted effort by most governments to control them.
https://www.astm.org/DIGITAL_LIBRARY/MNL/PAGES/MNL11466M.htm

They also put out loads of CO2 (much more than the other undesirables listed above).

sorry for leaving the door open after we passed through, we mean that electrical vehicles used as a sink for apparently excess solar generation during the day will be emitting virtually none of the bad stuff

It’s not really a problem worth worrying about.
And in any case petrol/diesel cars will be fading away over the next decade or so with EV’s taking over.

roughbarked said:

mollwollfumble said:

transition said:

>Why not, given that the exhaust contains nothing but pure CO2 and the noise levels are lower?
(I can actually see why not, it’s not either the exhaust vapours or noise. It’s the heat. Care is needed to avoid burning people on the hot exhaust.)

did you miss what I said about a cold engine and exhaust, how long they take to come up to temperature

Huh? I don’t see the relevence.

Are you claiming it takes too long a time or too short a time? And are you talking about engine temperature or exhaust temperature?

You don’t get exhaust temperature without engine temperature.

it’s called cold start extra emissions, which is part of what you’d need consider of the practicalities of side exhausts

Spiny Norman said:

It’s not really a problem worth worrying about.
And in any case petrol/diesel cars will be fading away over the next decade or so with EV’s taking over.

Once they overcome the 3 problems. Price, range & recharge time.

FWIW this is one of my road cars. When I give it a good prod on the throttle, it’s quite loud.

I also came up with an odd muffler design years ago, it was intended to chop-up the sharp exhaust pulses with the intent to lower the overall pressure spikes, thus making the engine a bit quieter. It has no baffling inside it so very little restriction.

Tamb said:

Spiny Norman said:

It’s not really a problem worth worrying about.
And in any case petrol/diesel cars will be fading away over the next decade or so with EV’s taking over.

Once they overcome the 3 problems. Price, range & recharge time.

Two out of those three are virtually solved right now, and the price is only a year or two away.

transition said:

roughbarked said:

mollwollfumble said:

Huh? I don’t see the relevence.

Are you claiming it takes too long a time or too short a time? And are you talking about engine temperature or exhaust temperature?

You don’t get exhaust temperature without engine temperature.

it’s called cold start extra emissions, which is part of what you’d need consider of the practicalities of side exhausts

or just cold start emissions, catalysts needs run over 300C maybe, and ambient temperatures can be low as -20C in some parts of the world

with multi-lane roads pulled up at intersections/stoplights you can’t manage your distance from a vehicle alongside, you can however manage your distance behind another vehicle, for example

Tamb said:

Spiny Norman said:

It’s not really a problem worth worrying about.
And in any case petrol/diesel cars will be fading away over the next decade or so with EV’s taking over.

Once they overcome the 3 problems. Price, range & recharge time.

Lectric vehicles could be swamped by hydrogen because of the problems you just shone a light on.

Spiny Norman said:

Tamb said:

Spiny Norman said:

It’s not really a problem worth worrying about.
And in any case petrol/diesel cars will be fading away over the next decade or so with EV’s taking over.

Once they overcome the 3 problems. Price, range & recharge time.

Two out of those three are virtually solved right now, and the price is only a year or two away.

Range 400km with aircon running?

Peak Warming Man said:

Tamb said:

Spiny Norman said:

It’s not really a problem worth worrying about.
And in any case petrol/diesel cars will be fading away over the next decade or so with EV’s taking over.

Once they overcome the 3 problems. Price, range & recharge time.

Lectric vehicles could be swamped by hydrogen because of the problems you just shone a light on.

Nope. Hydrogen is not really going to make a dent in the real world.

I would think showing pictures of racing car exhausts is a bit of a misleading example. Road cars are in a completely different environment.

Tamb said:

Spiny Norman said:

Tamb said:

Once they overcome the 3 problems. Price, range & recharge time.

Two out of those three are virtually solved right now, and the price is only a year or two away.

Range 400km with aircon running?

Yep. The latest & especially upcoming battery technology give a lot more range and can be charge far faster than the older battery types. The limit is the rate of how quickly the charging infrastructure can be build.

Spiny Norman said:

FWIW this is one of my road cars. When I give it a good prod on the throttle, it’s quite loud.

I also came up with an odd muffler design years ago, it was intended to chop-up the sharp exhaust pulses with the intent to lower the overall pressure spikes, thus making the engine a bit quieter. It has no baffling inside it so very little restriction.

Very interesting. Thanks for sharing.

JudgeMental said:

I would think showing pictures of racing car exhausts is a bit of a misleading example. Road cars are in a completely different environment.

FWIW the Mercedes G-wagon thingy has the exhaust out the sides. When it was introduced here the ADR that required the exhaust to exit out the back of the car was dropped …. and thus my Fraser (the car in the photo) was made (a bit more) legal. :)

Spiny Norman said:

JudgeMental said:

I would think showing pictures of racing car exhausts is a bit of a misleading example. Road cars are in a completely different environment.

FWIW the Mercedes G-wagon thingy has the exhaust out the sides. When it was introduced here the ADR that required the exhaust to exit out the back of the car was dropped …. and thus my Fraser (the car in the photo) was made (a bit more) legal. :)

My old landy had a side exiting exhaust, fitted by me. With a Hotdog muffler. sounded good. still went like an old landy though.

JudgeMental said:

Spiny Norman said:

JudgeMental said:

I would think showing pictures of racing car exhausts is a bit of a misleading example. Road cars are in a completely different environment.

FWIW the Mercedes G-wagon thingy has the exhaust out the sides. When it was introduced here the ADR that required the exhaust to exit out the back of the car was dropped …. and thus my Fraser (the car in the photo) was made (a bit more) legal. :)

My old landy had a side exiting exhaust, fitted by me. With a Hotdog muffler. sounded good. still went like an old landy though.

That’s something that would be difficult to improve on.

Spiny Norman said:

Peak Warming Man said:

Tamb said:

Once they overcome the 3 problems. Price, range & recharge time.

Lectric vehicles could be swamped by hydrogen because of the problems you just shone a light on.

Nope. Hydrogen is not really going to make a dent in the real world.

Do you think hydrogen fueled aeroplanes will come to the fore? Innovation in aircraft engines might spur innovations in hydrogen powered land vehicles.

Witty Rejoinder said:

Spiny Norman said:

Peak Warming Man said:

Lectric vehicles could be swamped by hydrogen because of the problems you just shone a light on.

Nope. Hydrogen is not really going to make a dent in the real world.

Do you think hydrogen fueled aeroplanes will come to the fore? Innovation in aircraft engines might spur innovations in hydrogen powered land vehicles.

butts in

I reckon not. Too hard to store in the bulk quantity needed. The best we can hope for in aviation fuel is liquid fuel derived from bio sources to replace some fraction of the fossil derived fuel.

Mind you, if someone cracks biofuels and makes it totally economically viable for aircraft then the same could be used in ICE road vehicles too. But there are problems of cost and scale and all that. Well known, it needs a big breakthrough somewhere, maybe GMOs.

party_pants said:

Witty Rejoinder said:

Spiny Norman said:

Nope. Hydrogen is not really going to make a dent in the real world.

Do you think hydrogen fueled aeroplanes will come to the fore? Innovation in aircraft engines might spur innovations in hydrogen powered land vehicles.

butts in

I reckon not. Too hard to store in the bulk quantity needed. The best we can hope for in aviation fuel is liquid fuel derived from bio sources to replace some fraction of the fossil derived fuel.

Mind you, if someone cracks biofuels and makes it totally economically viable for aircraft then the same could be used in ICE road vehicles too. But there are problems of cost and scale and all that. Well known, it needs a big breakthrough somewhere, maybe GMOs.

I suppose one thing that needs to be evaluated is whether hydrogen can be mass produced in quantities cheap and plentiful enough for an entire hydrogen economy. One good aspect is that hydrogen could be produced using excess electricity so that the grid is always producing something when there is lots of sun and wind.

Witty Rejoinder said:

party_pants said:

Witty Rejoinder said:

Do you think hydrogen fueled aeroplanes will come to the fore? Innovation in aircraft engines might spur innovations in hydrogen powered land vehicles.

butts in

I reckon not. Too hard to store in the bulk quantity needed. The best we can hope for in aviation fuel is liquid fuel derived from bio sources to replace some fraction of the fossil derived fuel.

Mind you, if someone cracks biofuels and makes it totally economically viable for aircraft then the same could be used in ICE road vehicles too. But there are problems of cost and scale and all that. Well known, it needs a big breakthrough somewhere, maybe GMOs.

I suppose one thing that needs to be evaluated is whether hydrogen can be mass produced in quantities cheap and plentiful enough for an entire hydrogen economy. One good aspect is that hydrogen could be produced using excess electricity so that the grid is always producing something when there is lots of sun and wind.

At present hydrogen can only be stored under high pressure in heavy cylinders.

Spiny Norman said:

Tamb said:

Spiny Norman said:

It’s not really a problem worth worrying about.
And in any case petrol/diesel cars will be fading away over the next decade or so with EV’s taking over.

Once they overcome the 3 problems. Price, range & recharge time.

Two out of those three are virtually solved right now, and the price is only a year or two away.

Range? I haven’t seen any with a decent range.

Michael V said:

Spiny Norman said:

Tamb said:

Once they overcome the 3 problems. Price, range & recharge time.

Two out of those three are virtually solved right now, and the price is only a year or two away.

Range? I haven’t seen any with a decent range.

The latest Tesla has something like 900 – 1,000 km range.

Witty Rejoinder said:

Spiny Norman said:

Peak Warming Man said:

Lectric vehicles could be swamped by hydrogen because of the problems you just shone a light on.

Nope. Hydrogen is not really going to make a dent in the real world.

Do you think hydrogen fueled aeroplanes will come to the fore? Innovation in aircraft engines might spur innovations in hydrogen powered land vehicles.

I’m not sure, but it’s possible. Back in the 50’s Lockheed were looking at making a high-speed spy plane that was fuelled by liquid hydrogen.
Suntan

Spiny Norman said:

Michael V said:

Spiny Norman said:

Two out of those three are virtually solved right now, and the price is only a year or two away.

Range? I haven’t seen any with a decent range.

The latest Tesla has something like 900 – 1,000 km range.

Once the cheaper varieties get there, I’m in.

Michael V said:

Spiny Norman said:

Michael V said:

Range? I haven’t seen any with a decent range.

The latest Tesla has something like 900 – 1,000 km range.

Once the cheaper varieties get there, I’m in.

Yeah. The battery technology coming in the next couple of years will make that happen I reckon.

Spiny Norman said:

Michael V said:

Spiny Norman said:

The latest Tesla has something like 900 – 1,000 km range.

Once the cheaper varieties get there, I’m in.

Yeah. The battery technology coming in the next couple of years will make that happen I reckon.

That range would suit me. Any less becomes somewhat iffy. There’s plenty of chargers around (motels in particular are installing them), but it still takes time to recharge.

Michael V said:

Spiny Norman said:

Michael V said:

Once the cheaper varieties get there, I’m in.

Yeah. The battery technology coming in the next couple of years will make that happen I reckon.

That range would suit me. Any less becomes somewhat iffy. There’s plenty of chargers around (motels in particular are installing them), but it still takes time to recharge.

I’m still wondering about battery life.

If i buy e.g. a Tesla, and have to cough up thousands for new batteries when it’s, say, 20 years old, then that’s a different proposition from having to go to that expense after five years, and every five years thereafter.

captain_spalding said:

Michael V said:

Spiny Norman said:

Yeah. The battery technology coming in the next couple of years will make that happen I reckon.

That range would suit me. Any less becomes somewhat iffy. There’s plenty of chargers around (motels in particular are installing them), but it still takes time to recharge.

I’m still wondering about battery life.

If i buy e.g. a Tesla, and have to cough up thousands for new batteries when it’s, say, 20 years old, then that’s a different proposition from having to go to that expense after five years, and every five years thereafter.

Don’t buy Tesla. Go with one of the big Japanese car makers, and get a lease or guaranteed buyback deal.

Spiny Norman said:

It’s not really a problem worth worrying about.
And in any case petrol/diesel cars will be fading away over the next decade or so with EV’s taking over.

What, me worry?

I’m just interested in whether it is better. Less junk under the car to get in the way of mechanics. Lower cost (perhaps) and higher performance, with no obvious downside.

I mean, everything’s a trade-off, but not here?

transition said:

transition said:

roughbarked said:

You don’t get exhaust temperature without engine temperature.

it’s called cold start extra emissions, which is part of what you’d need consider of the practicalities of side exhausts

or just cold start emissions, catalysts needs run over 300C maybe, and ambient temperatures can be low as -20C in some parts of the world

with multi-lane roads pulled up at intersections/stoplights you can’t manage your distance from a vehicle alongside, you can however manage your distance behind another vehicle, for example

Oh, so you’re in favour of side exhausts and catalyst in the manifold then. They heat up quicker to reduce cold start emissions.

mollwollfumble said:

Spiny Norman said:

It’s not really a problem worth worrying about.
And in any case petrol/diesel cars will be fading away over the next decade or so with EV’s taking over.

What, me worry?

I’m just interested in whether it is better. Less junk under the car to get in the way of mechanics. Lower cost (perhaps) and higher performance, with no obvious downside.

I mean, everything’s a trade-off, but not here?

the muffler and length of exhaust reduces chance of sparks (chunks of hot carbon perhaps) being blown out while still hot enough to start a fire, which in summer whatever many parts of the world is important

two-strokes and two-stroke diesel probably be quite bad, perhaps rotary engines too not sure, but there’s always a chance with combustion engines

exhaust pipes and mufflers are really helpful in many ways, even better if got no holes in them

I had fantasies once about pipes out the side of car, I worked across the road from the police station, of course the policeman had ideas too about what appropriate exhaust pipes were, they differed to mine

captain_spalding said:

If i buy e.g. a Tesla, and have to cough up thousands for new batteries when it’s, say, 20 years old, then that’s a different proposition from having to go to that expense after five years, and every five years thereafter.

The latest Tesla batteries are expected to last 1,600,000 km before needing replacing. They should last about as long as three chassis that they go in.

Spiny Norman said:

captain_spalding said:

If i buy e.g. a Tesla, and have to cough up thousands for new batteries when it’s, say, 20 years old, then that’s a different proposition from having to go to that expense after five years, and every five years thereafter.

The latest Tesla batteries are expected to last 1,600,000 km before needing replacing. They should last about as long as three chassis that they go in.

Jazus, I’ll get one for the Redoubt.
How much do they cost?

Peak Warming Man said:

Spiny Norman said:

captain_spalding said:

If i buy e.g. a Tesla, and have to cough up thousands for new batteries when it’s, say, 20 years old, then that’s a different proposition from having to go to that expense after five years, and every five years thereafter.

The latest Tesla batteries are expected to last 1,600,000 km before needing replacing. They should last about as long as three chassis that they go in.

Jazus, I’ll get one for the Redoubt.
How much do they cost?

Quite a lot, but they come with a free car.

Spiny Norman said:

captain_spalding said:

If i buy e.g. a Tesla, and have to cough up thousands for new batteries when it’s, say, 20 years old, then that’s a different proposition from having to go to that expense after five years, and every five years thereafter.

The latest Tesla batteries are expected to last 1,600,000 km before needing replacing. They should last about as long as three chassis that they go in.

As I doubt Elon would ever exaggerate then this must be true.

reckon quarter milers use that arrangement to keep some extra force down on the tarmac, no small amount of fuel they burn and exhaust gas produced, it’s also a simple pipe system that can be bent up and cut, doesn’t obscure forward vision, and perhaps less likely to ignite the earth or crack the concrete, whatever, compared to facing toward the ground. Points the noise upward also

thinking too all exhausts of normal vehicles are deigned to allow for engine rock on the engine mounts, which is accommodated by (rubber) hangers along the length of the exhaust system, plus flex couplings where needed. The flex couplings i’ve seen aren’t made to flex much, and I gather of (especially) petrol vehicles that they don’t leak at all would be really important, over the expected life of the vehicle. Worse case situation with a petrol car would generally be a running stationary vehicle, an engine not up to proper running temperature in case of a catalytic converter, windows up probably (of just the one vehicle), and the recycle/fresh setting on the heaters/AC depends on few variables, but it matters

anyway the geometry of going out from the centre line of the what the engine rocks around increases the radius of the arc, so circumference travel, if you will

the exhaust hanger requirements change, or you need employ a flex coupling

assuming a solid exhaust with converter and muffler near as possible to the engine manifold, that’s quite a bit to squeeze in (plus local heat), the usual arrangement with a full length exhaust is the exhaust can sort of be tucked away, muffler and all, along the length of the vehicle

i’m pondering now the extent the length of exhaust is a heat sink, or heat radiator, which I guess it is really, it doesn’t just take the gas away quietly, it takes the very hot gas away. You know the manifold (and turbo) etc might glow orange hot at high load, there’s still some gas expansion maybe from the tail end of combustion, and with a turbo added pressure from driving it

i’m thinking the entire length of pipe to some extent is a muffler, I mean the volume of the pipe alone is not insubstantial, it could be similar to the volume of a muffler, or quite a bit more, and some equalization of pressure pulsed from combustion must happen in the pipe also. With turbo the pressure pulses are much less

also i’m wondering if you run a muffler much nearer the engine you need better mufflers to run at higher temperatures

it may be that the exhaust gas cools quite a bit by way of expansion between the engine and outlet on the tailpipe, there’s also heat dissipation along the length of the pipe

just some thoughts